SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '502c4aef847803ba991e3610e521750dd74e848e863b07cc846005719668a3ac' 
  AND token = 'OqsSmbWRvNR1wZ03QZslbmDn+PkKA5kj7ijff60Wq4E=' 
  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"
    }
  }
}