SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6de7dc88392d8dffb435cd52069b1757b0f731c300723c2e02fd8b815bcafa9c' 
  AND token = 'f9g2kMm1OTdWpGCrUicWHSK67KXOsVJ31JlsEzwWRB0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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