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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b0f1d04b8fde7b06a56e4dbc4933a40ad96b5e0867f6cffbc84c4cfe98967e21' 
  AND token = 'XnLAKr+fw4FGiDRrdYyW0iVxrJxQqRiPv6w7x964sqM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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