SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df2a86c5878a1532c5787145513b5db4e3e42094d042de34a233eb6092aade13' 
  AND token = 'LGzctYtFzRUlFtBILT5LeVDkE24u4j5f0eOsq8fARks=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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