SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a525c1ca3c78d1da69c487fd2546c5f13c6e9adbf6b502ce2d0b4c6c65bba757' 
  AND token = 'gkZ4udUOgAAKEsFNsFKuAcbORTUx6iGq6gHzzGW7tPo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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