SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dbb3a2ec3c9457dc10b8d54e06ba3dc262041087339693f406147640576197d8' 
  AND token = 'uZ4kcaGIlF3ol8GudriUSryCrI/2ts2REZEQhFoL1YA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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