SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73d5899cd19878fd43642bb40ef1f49e97d63a311eed823a59a1bffed4faba2c' 
  AND token = '6RO2LgeK5JdtjGO6TEw7he/lqZ7uJ0vY+YofwkjpL+Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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