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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8a7a1ddbeb77576287ff1b7bc207ec523c96906d886365c40fe3e5e53e79d37' 
  AND token = 'mx1M9CczirXRdzyTEGrkppiJdcG5rm5+VX45/mT2xm4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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