SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb007348cb6519e079a4db142fb5971a6094649ebc435c80b80f5596c02a6723' 
  AND token = '3WawsTpT4rBFeXy2lXjYlmKLRLJq3nHRie2eZWiwz+c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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