SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a7dc0b6fb7826a51aba4223fa5a6f7081f0335538c528310b7491acc70e87f12' 
  AND token = 'y7Jp5FmRSyzuUTBsV2dtG1MO0S3NQ1RXosdqZtQC4Ts=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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