SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e6ec498e4e009c0846ce4036e1dbf3b7ad5266d326fc30748a183b0457dbede2' 
  AND token = 'wYfenY3JGSTtQ4IRmXtXdrTQWA1Tr7vGdr2iVuSRpgs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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