SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'defc1db24fc27111eabdca21edd5291c63d3070d2b391806290da448f503a319' 
  AND token = 'NUIcLmSxXYN1/tCrOxfQZlcsEIsMuo1UrkNBUn4fPmc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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