SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39e8feba5cea9bd28c68ecfdbfa3c30da10b353401a0b764f3c93aa3175892dd' 
  AND token = 'Fpr/MyvQMjY4Zi6N1esXuF2IWeGWe3CUlH2xclkg3iM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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