SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '44c040f0d99cbf8f86e377a090db28961306efcc848de92c5bae480a38051b91' 
  AND token = 'UBvTh0bpVq5N3dRh7kkgK+NFkDuFcUOwbOmbwp9YaJo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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