SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '406147636bd1a03d67d2bbbd32e295ddfb4d201ec5e89e2bd1d890d518003b78' 
  AND token = '+pzFBXjz9fFU6AkchCBAFASsGwvH4zB+R2Ixg3YtrLo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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