SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6bf5f7e804c8bce306f818d8d42a1e035c4a1a28c158c688ead8650fd66947d' 
  AND token = 'kBxZUE3QTEcCpiAbToTXUjvFpUeYDinMDteCsoj9VfU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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