SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd9e4e3a8f63e82fb318ebd35526674d35aece2340d16add616f00d748fffa88e' 
  AND token = 'O9PT1RnTLJOEZ2DQeCJpDL5rVuGL6rGvNO6BrmvKHhY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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