SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e28a8d8026d40500789e621f6e5ad430af34a2189f173a7b4ea5fdff4979447a' 
  AND token = 'FYsg3FbQnID7ftzct+eHBxOyeFhmzkjNrpX7PYKZsnE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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