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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6f88cbf7058c45f936e8aa89bf8b1930f0df5a613fd954de8a267de6f0b3c20' 
  AND token = 'dUavdR/3JYEscuM4DfhQLhQCfc8WtVmXKh75GBRj4Ac=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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