SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '23c529262368e77e251995bf1a1e68c567d7991f391defd5b43806a0619136a9' 
  AND token = 'r7vrqm5M5JinPIh8TzXYFV/GNfqf/1VaF9Ghq9RjKyA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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