SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '761242211c77a3987b5ee9d2bdf6700600291483a0556f0057d515feb871593a' 
  AND token = 'Au3YATQnQgiICGss2+mqKKPwAZapHaiiz0CHodO/kQs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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