SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8793801fcc08aaf7548592b99c6e64667dde6a12772044791248963e7bff3ab9' 
  AND token = 'U+eOs8RnoBvDi4cu8gkWpmzWwoeEQWrULYMf3FbUo1U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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