SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '669ba72f2c8f3a9bc5808048acc5fb21c2cabd007e027a300a3f559cca877101' 
  AND token = 'DFV91EHaVzvAdpD5qHfrMQilocxm1Tv1MuWqUespaq0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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