SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '033c66070c286dc24369bf45a0061176208b5a82982b9c0f0ca7b871088e3e72' 
  AND token = 'PfyqlsQ/siyFPpVgYQGJxYgrMGL5DkYhjEytMxs4irk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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