SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e15b1d89e96c43af13644c97ef0e86d4768f20934fd154b87bff5e16d7825567' 
  AND token = 'jPzyXbVDNGAumqrQORuaflLOOGVtDFWcfQDbpLzNWBM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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