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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '290f4e8df4a069a3aa974b48f77e767d8c1c5d2ad2b609e73ff1bb7a27fc10ca' 
  AND token = 'gUuCNUE4AD3mOrh+lJQFLsHDRo064qbAbCP0EFrEuVQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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