SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6340a31b091550b0b1ce1926abbf69c56bba7d58b397b69a138a2aa8f0ecb515' 
  AND token = '71KV3OVnBKTPeE/9ZUuSKxZG8u6t4gQydWoxCUomWyw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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