SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3fef593a76234ba5ffe74871d25ece7ee3fe88f5d2cf20cd64f63e9880c40f45' 
  AND token = 'EUIXk2xiQ1eU/rqxv0b/v5rtdrhoyNB7+6GkoNh/Pik=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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