SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52439fe2ad802df71ec3b9b21c572cb7811a1cb86176706f00fa431faeb9e79f' 
  AND token = 'AOqiqQDiT0WKBiwDAc0QjXkVvEPclcRMMWOdW5pop1c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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