SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9ef80b638b67448ee7dea8577a2918905352d2cc2ce45e85b789314bb774b95' 
  AND token = 't4JNJlvIOaZKJHxByJ/FGG8x/kJ0hRFc2wZZjvgwtlE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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