SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'be106beffd7950020ac9f088e25468ddc467481fa1b005e967a4d74b7b713b70' 
  AND token = '51SQOQOxpOv+eSywLy8ayr9EiAM5AdiKc1PG9/iu0yQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}