SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '139d733eaa8d0b604f820671a5a86da00450e2f628c8b89609fd6b90aa5eb9c5' 
  AND token = 'ZoTuoBxJnnWUNqO8mxm+3tSySzgMLs5BFsS4yuKuI0I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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