SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76899a8d43c0ffc0d0a4b3aa4a4c4d96a4c59a6212e4aee85162fb696e56ab8d' 
  AND token = 'lWG8grBSUcFtI7GsjXBdStorJNnhrZLyxMhafEf6278=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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