SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3176eed1b3c6853cc66c7c3bbf711897523eef393ddc7af05a194e75ab8533b' 
  AND token = '6CUXhwlft4KLBowMg8TCoUGSmnLwPNdn06MC/nk2xK8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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