SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b99dc9f1e6d8635c5aafacf41b454bdf94d9764765184f6445f3256be04b7007' 
  AND token = 'qjt1/TLO+q9tEY2/VmRD3rBcoBuCyMoxm8ujDjvcIWw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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