SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b967e76cba2004392d82d8e9e07a7038d5aea4153e2440d5326325a183043f5a' 
  AND token = 'OXcskntKO2DEroxoItzbafe2FAbmj4MD4iS2+zGU+nU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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