SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a941acc2e188c7bb0eaf4e4a2f4a3d607915ad3a0f61f2621e43277d2dcc859b' 
  AND token = '0SvIHPucMlzxwZdRYr3ZgNBBciKXXIPPi4pFPvOob6Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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