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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9a88f6e50eebc3ceb5ee3f562dbfb1dbeb9a3d92c92c05a8d0a1ae2ab591dae' 
  AND token = 'UndbEB084KzPA0trhhsn1SFWHLPRlULglasoEdL0lJI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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