SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6ec0b38240f6940c096afdced97fcd0cc65d33f52268386af66c72ac0cef192' 
  AND token = 'bXsHqF1YeAZdgRbCYxQwHRfJOzjInNW9ahaM5JiP4+Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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