SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c91412530ce1d75477269b34ae83108cd67455ae793163bb4edf8afe1b10cabd' 
  AND token = 'k5xNlvFq5JMpTdp/GsXyVrTg7dr3D0Uh+GBYTSRKoWU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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