SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c2bba3f996fb437de7fd51695616fa57e475055f929d5afd8df7c67560f70221' 
  AND token = 'RkSSEHPgL89svTTlEZ4d23bk79RtmtWiiplgOBdNChE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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