SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '88635166a389b8ef76c719c1eac24505bcbffbfa1afda450c1a2a506cf04d473' 
  AND token = 'LOoDF92GpnulftuebV4bNXRWfvGMvoG2HkHkxBUclv0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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