SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91d690c0287fc068a065c18139f57dda4eb11fec5bc3ca6797420197073d3a55' 
  AND token = 'GCNL8vBXLYvIu8IjtUSIsp0gSeOJzohPrhaPwhCz2oc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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