SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '98f43921bebea3359b35696e9fb1b7cd1f6db628c3a1a6c3e35742197aec39a0' 
  AND token = 'D4ExSGFQnNiyqSeBPxQvoKQZkibh11Ahsg9Be4/jMDo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}