SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1c8757640a6684509d01bb00bd3f71f856353827524452b3112ef075344e430a' 
  AND token = 'vwOmTG7pUEW7WEMIW20ceUx85RVGD+W5wb4yn4bfLaI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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