SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9cf30300863d7335f343aabd05ad8ab0829182de45a8723b765d18a7341ad1e5' 
  AND token = 'R7RKwfbDQE9FpG04GGY3kVP6moSSrkDYifCSezNLbMk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}