SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5620b7f57110847269dd5eaa015c851142b5da32791e9dd1776574c068c7bfbd' 
  AND token = 'c5Ht8W0UXdV2sXavff8JHWLkwsxVHY4dqnjdB0MITH8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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