SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3dde7aeaa549790e884650cf330e3bcfde95b2d0a465251c148e712261ecb0d0' 
  AND token = 'xePtubscbkYiSErfAQpI47ZLc9MhXQzoUpmiGlm3aVs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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