SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a51f1e298e6009e101d989c6bc96ca48913b18ec3bd0c941c4518c02709955c0' 
  AND token = '0vyoMQ1rtHXzqxzART9hLeO3ykcsr0jNNatoeRNTzCk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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