SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4344abd993268e818d9b41260e46ef7660bf5433dd2675d9279235531a993c87' 
  AND token = 'gY/lgyda/EXIDnwrtpdCMvEZf0xotQzYUE1Jt5wLpnc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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