SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '983a1a5a97a32eb209a424b5d2e65ee5b2d9304f81157820c612935a1cbef4cf' 
  AND token = 'Cq/H/R1fXmvDGtTxVPGS3mqIyMP7j4twB6QUXE0gDiY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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