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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '189af42934d9e1016f766ab0b6c97654036962ed9c71f644c06a7984bc2c0c37' 
  AND token = 'MmOQlum08jQjHhpENiBBXHow5k76YF0ZWZmk/DJytrY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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