SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28cd46139c07ff9885060713d0791236a937fe2042b0954999f64cea677eff42' 
  AND token = 'uha97U7p5UQ5DtVl0F0Q+ltHhUjjxE442p2mcyhUlio=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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