SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '31711d94a3302d0a86bf75f9c6f5e3e498f146c851f268c8a74fcfae36f28d14' 
  AND token = 'xFWZNXqE/YOs5PEi1UrPI8nFR4O3T4KD0fXy2VKu390=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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