SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6213799d0a26d77bff19cdf1f654944b772fe1421cc2d2caeb2d11e279861675' 
  AND token = '2/E+0Xl+AVrW3IdysjnAKiiwSm6EUzQ6nJuvZHChTQQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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