SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4e48ee0097579e8a7865fd6592d0ea91fce27eaeabbeb46ff6f4f9cfa291fdc4' 
  AND token = 'QPVQaha8glAdKN5oQOmcjcTq07knKMEQvihk+10eVEw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00045

JSON explain

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