SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd6ba08115a64ca174eddea39820326ead224e1e90796562fad4098d8d1aaa303' 
  AND token = 'YrhnIU02ZjMvVmoJjrWj3xO9EEUhGvUCIk/uqozJxQg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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