SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '787a0fb1ebbd6d5bca85b28fca05a01c7679832cf937c1e6f7d20a5047b50a94' 
  AND token = '1rjuO8zVMOShpEpFT5j6SGjmH4qYFF7RSbRGzKnMgNs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}