SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6fb2a2f667c6d9decb4dc55a98233616664a0f493e426215c288297fba4d64ab' 
  AND token = 'WU1NVfQZJoI9p43INDiXlurN0IcpAZ6OjEThfK3unbM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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