SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7f56ee5abf48da4667383e9c7d6255c5affc70d1defdfc4f413c619258022a36' 
  AND token = 'uigIo6ccMDWRTU1uwSPszcyLiWv4xga/3SkkY3oGlYQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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