SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1c800f0180e500fc53a28563ccbec4e2b7a6892903bab1b414ac270990547ec7' 
  AND token = 'nSRkMdNiNjceR3PBBgf3ojGGmGcYYxgoUdpMvff4hQM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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