SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e0b7189d35397ed03b736099f6385fe423c4d905b36433b855f6c0833944e15a' 
  AND token = 'LnL+df40T3B460yPzRThs4oIaRjFb+cw3xCvBQxACrM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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