SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68965877d141d30d3224e26f01213acc2446fb8d3e1d929469f9d4b31ead3549' 
  AND token = 'kysThppDffPHjqfY08yhsRDm7Zb4QszQKPcc3lDgIdc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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