SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f6217881f9cbb0617282b598b0c1d232768bffbcc75e483120824cde4422d23' 
  AND token = 'Y1S8w6cLknvyd+70YhtYqawrd2UClyM9cMj5p0s3Epg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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