SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '350c1cdb944eb9197e19f38d605d9244c465249e0a0f76e79545fd7f39dc1548' 
  AND token = 'gBt1jh/Amsfv+wEBKsAEH7+apy/FKJxTONHq4hARuBQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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