SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'abe16e633161ab13034e0da3139a463819de6d144fca025acbced37e620f192d' 
  AND token = 'YVrwnMyLjaGAOGUzTdQOO+Z8gai/URTcVaT17h7vHw4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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