SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc9b3ddce4d5ef858fddb50790d4173bf5beea9699f30284944eeea6b3860df2' 
  AND token = '8giTbvlonH1aMAHKhtqLnuNh3RhMfYYFKZP7yvjF8bs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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