SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e4203362d8323610436029f0a36d0ff57253e958599371cfceecaa193480034' 
  AND token = 'ltXiiHkrAbTtIqpVIIbeMiVlZkTzSKTjWF5WVe1GLPY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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