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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e6f2ad6931f026afb034e7210c69fd63a7d1bc4fcdcf4f81640a7eb92a23641' 
  AND token = 'bYcauUkYMyE3AYlvmMn76MvarPfi+RXR1fviN4kQLEY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}